1GA51_0e - Rohde & Schwarz
Contents
1. Active speakers eliminate the need for an additional power amplifier If a power amplifier is needed the maximum continuous output power should not be higher than the power rating of the loudspeakers 2 2 Test Setup 2 2 1 Test Room As the speech send sensitivity of the telephone has to be measured in free field the test room needs to be sufficiently anechoic in the measurement frequency range To accommodate the speaker arrangement as suggested below the test room should have a minimum free space of about 1 5 x 1 5 x 1 5 m Furthermore suspensions or supports have to be provided in the room at the required loudspeaker positions 2 2 2 Loudspeaker Arrangement For a good spatial distribution a minimum of four speakers is required The optimum arrangement for four speakers is a regular tetrahedron i e two speakers are positioned near the room floor in two diagonally opposite corners of a virtual cube The other two speakers are positioned in two upper corners of this cube which are not above the first two speakers Eight speakers should be positioned in the eight corners of a virtual cube If possible the speakers should be inclined towards the MRP To assure the spatial uniformity of the noise field a minimum distance of 1m between each of the speakers and the MRP is recommended Rohde amp Schwarz Generating the Noise Field for Ambient Noise Rejection Tests 1GA51_ Oe 7 General Description Deviations from the idea2. the spectrum level and spatial distribution of the total noise field is verified 2 3 2 Spectrum Adjustment Using the Adjust Spectrum function of the ambient noise field calibration Calibration gt Ambient noise field of the R amp S UPV K9x software provided with option R amp S UPV K91 the 3 octave spectrum of the pink noise is adjusted as far as possible to a flat line by trimming the respective 3 octave gains in the respective equalizer channel 2 3 3 Level Adjustment Rohde amp Schwarz The level of each speaker has to be adjusted to 24 dBPa A 10 logign with n being the number of speakers With four speakers each speaker has to be adjusted to 30 dBPa A with eight speakers each speaker has to be adjusted to 36 dBPa A The level adjustment function of the ambient noise field calibration of the R amp S UPV K9x software can be used for this purpose Generating the Noise Field for Ambient Noise Rejection Tests 1GA51_0e 8 General Description It is suggested to take the number of speakers into account by first adjusting each speaker to 24 dBPa A at MRP and reducing the gain in the amplifier or equalizer by the appropriate level difference before activating all speakers 2 3 4 Overall After all speakers have been adjusted the total spectrum and level are checked first at the MRP then at 0 15 m distance around the MRP in at least 6 orthogonal spatial directions This can be either done with the separ
3. to check the total adjustment If everything is within tolerance check spectrum and level for a number of points in at least 0 15 m radius around the MRP At last place the measurement microphone at MRP again and click or press softkey Start Measurement Spectrum and level at MRP are now measured and the tolerances is checked If the result is within tolerance it is stored as calibration value for the ambient noise rejection measurement A report can be generated and exported before closing the window with the result of this measurement 53G Ambient Noise Adjustment Miel Frequency esponse Margin 5 86 dB 25 dBPa A lt Amb Moise lt 23 dBPata Unweighted spectrum dB l l l l 63 100 1000 12100 Frequency Hz WE Measured Noise 23 80 aBPald YM Upper imit BB Lower imit 3GPP Hands Narrow Diffuse field microphone CMU 7 CET Save Curve 4s Ee Enter cose Save Curve Ag Load Curve Lint Bile PE cee Cae Change Scale Create Report Close 3 3 6 Performing the Test Rohde amp Schwarz After step 3 3 5 has been completed successfully re install the HATS or LRGP test head respectively in the test room with the MRP at its original position Establish a call to the mobile and start the test case The noise field must be present when the test is started During the test execution the operator is prompted to switch off the noise field This can be done by stoppin
4. Generating the Noise Field for Ambient Noise Rejection Tests Application Note Products R amp S UPV R amp S UPV K9 R amp S UPV K91 This document describes how to generate the noise field for ambient noise rejection tests according to 3GPP TS 26 132 sections 7 9 and 8 9 Application Note Thomas Lechner Feb 09 2010 1GA51_0e Table of Contents Table of Contents 1 AG CO ost ccc rece EEE 4 1 1 3GPP Mobile Phone Tests R amp S UPV K9 UPV K91 ccc eseceesecseeeeeees 4 1 2 Ambient Noise Rejection ANR Tests scceeseseeeeeeseeseeeeeeeeeseenesnenes 4 1 3 Requirements on the noise field ccccceceeeeeeseseeeeeeeeeneeeeneeeesenseeensenees 4 2 General Description cccceeeeeeeeeeeeeseneeeesenseneeeeseneeeeseneones 6 2 1 Required Equipment iis vei sc cencscossneesanetaenece ver swurcccntonvedecasnisianticeiersssiadestiveiestxant 6 2 1 1 E dup GS aaa castes etre nein eeceesta EE AEE 6 2 1 2 Audio CD with Pink Noise Signial cccccccecsssseeseeeeeeeeeeeeeeeeeesneseeneeeenees 6 2 1 3 CGD PAV Ol ecien Er oeseri erana 6 2 1 4 E GUNZ OT ea 6 2 1 5 EO UCSD GAIN S cira N 6 2 1 6 Amplifier required with passive loudspeaker c csssseeseeeseeeeeeeees 7 2 2 LEE EEE e A A N A A E E A 7 2 2 1 TESI ROOI opresi EENE EEEa 7 2 2 2 Loudspeaker ArrangemMe nt ccccesscceccsseceeceeeeeseeseneseeneenesoeneeeesenseneesoness 7 2 2 3 OTIS CUNO INS osc scenes ceceee
5. ate spectrum adjustment and level adjustment functions of the ambient noise field calibration or with its Measurement function Note that the last Measurement is stored as calibration value and has therefore to be carried out at the MRP Rohde amp Schwarz Generating the Noise Field for Ambient Noise Rejection Tests 1GA51_ Oe 9 Implementation with Specific Equipment 3 Implementation with Specific Equipment 3 1 Equipment List The following table lists the required equipment for n loudspeakers Equipment for Pink Noise Generator Audio Analyzer R amp SPUPV Rohde amp Schwarz Base SW for Mobile Phone Tests R amp S UPV K9 Rohde amp Schwarz BNC T connector Not specified Adapters BNC XLR male R amp S UPL Z1 2 per set The standard cables and adapters may be replaced by custom made cables 3 2 Connections AES EBU IN _ D Player_ DIGITAL OUT COSA AL OPTIGAL AES EBU IN w Onn QO ge O OF a bo kh h k OUTRI OUTL Rohde amp Schwarz Generating the Noise Field for Ambient Noise Rejection Tests 1GA51_ Oe 10 Implementation with Specific Equipment 3 3 Adjustment 3 3 1 Settings of the Active Speakers Set Power Mode to On Set Mute High and Mute Low to Off Set the Input Trim control to minimum 6 dB Set Low Frequency Room Compensation and High Frequency to 0 dB These controls may be used later on if eq
6. e red limit lines With a total level of 24 dB A the average 3 octave level is expected around 35 dBPa unweighted Generating the Noise Field for Ambient Noise Rejection Tests 1GA51_ Oe 12 Implementation with Specific Equipment 3G Ambient Noise Adjustment a 5 i a 1000 Frequency Hz 30FF Hands Margwe Diiue field microphone CMU CBT Set the gain at 80 Hz and 10 kHz to minimum Adjust the spectrum to a horizontal line by increasing the gain for frequency bands where the level is below the average and reducing the gain for frequency bands where the level is above average Once the spectrum is sufficiently flat click or press softkey Stop Adjustment in the user interface of the K9x software 3 3 4 Level Adjustment for one speaker Rohde amp Schwarz Start the Adjust Level function HIG Ambient Noise Adjustment Coarse r dBFPaA 3GPP Hands Mancow Dilluce field microphone CML 7 CET Press wheel 2 on the equalizer to activate the sum gain on the right end of the display Adjust the level to 24 dBPa A using wheel 1 Generating the Noise Field for Ambient Noise Rejection Tests 1GA51_ Oe 13 Implementation with Specific Equipment 3 3 9 Checking the performance of the total setup As soon as all speakers have been adjusted separately set Gain offset EQ in the utility menu to 15 and switch on all speakers You can now use the Adjust spectrum and Adjust Level functions
7. ea oceenseneterctaxcennanee E 8 2 3 AdIUSMEN soenda Ea aiaa Enea 8 2 3 1 Order of Adjustment isis cacescecenideaenctineni caren iiuetsanasiwacennunicussinerevinsnedsrdivedenwears 8 2 3 2 Spec rum AGI USIMGS ING sesirih rE EEEE EENAA 8 2 3 3 L vel AGIGSUMIG ING sinisira nisamie anea EEA EEEa ES 8 2 3 4 OV CI AN esnin EEEE EEEN 9 3 Implementation with Specific Equipment 00 10 3 1 LTS LIS aes hn sere rs inaano Eaa 10 3 2 MOINS CU OINS eeina iE NEEN AEE REE EEEE nus 10 3 3 AMUSING eoa E E 11 3 3 1 Settings of the Active Speaker ccccccsceesseeeceeseeneesenesensessenseneesenenes 11 3 3 2 Basic Settings of the EqualliZer ccccccceseeeseeeeeeeeesseeeeeeeeseeeeneseeneeeaees 11 332A T ONIN cean EEE ETEEN se secnecenccen st acdayexteetenece enecenst 11 3 3 2 2 Utility Menu asses eceeceaate ccc acca eee aes a ede descnetvennecececesseeeeascgesesseetsces 11 3 3 2 3 0 2 ee eens eee enn ne rere ie nee sneer ARENE aE 12 3 3 3 Spectrum Adjustment is ciicvciedectveseacenradensensaristupersnaiedstieeecescaseasadeesieceriwasewse 12 3 3 4 Level Adjustment for One Speakel cccccecceeeeeeeeeeeeeeeeeeeeeesenesseneesaees 13 Rohde amp Schwarz Generating the Noise Field for Ambient Noise Rejection Tests 1GA51_ Oe 2 Table of Contents 3 3 9 Checking the performance of the total Setup cceseseeeeeeeeeeeeeeee 14 3 3 6 Performing th T CSE cscs sie ccantcerastietennbiecsanwe E E AE E 14 4 Lit
8. edicated service network in over 70 countries Company headquarters are in Munich Germany Environmental commitment e Energy efficient products e Continuous improvement in environmental sustainability e ISO 14001 certified environmental management system Certified Quality System ISO 9001 Regional contact USA amp Canada USA 1 888 TEST RSA 1 888 837 8772 from outside USA 1 410 910 7800 CustomerSupport rohde schwarz com East Asia 65 65 13 04 88 CustomerSupport rohde schwarz com Rest of the World 49 89 4129 137 74 CustomerSupport rohde schwarz com This application note and the supplied programs may only be used subject to the conditions of use set forth in the download area of the Rohde amp Schwarz website R amp S is a registered trademark of Rohde amp Schwarz GmbH amp Co KG Trade names are trademarks of the owners
9. erat re cianiar a 15 5 ADDrEVIA ONS yacen aeaa 15 6 Ordering Information cccccscceseeeseeeeeeeeseeeseeeseneeeneseeees 15 Rohde amp Schwarz Generating the Noise Field for Ambient Noise Rejection Tests 1GA51_0e 3 Background 1 Background 1 1 3GPP Mobile Phone Tests R amp S UPV K9 UPV K91 As a supplement to Audio Analyzer R amp S UPV Rohde amp Schwarz provides options R amp S UPV K9 Base SW for Mobile Phone Tests and R amp S UPV K91 UMTS GSM Mobile Phone Tests which can be used together with Universal Radio Communication Tester R amp S CMU200 for acoustic tests on mobile phones according to 3GPP TS 26 132 One of the test cases specified in 3GPP TS 26 132 is Ambient Noise Rejection which requires equipment for generating a diffuse sound field in the test room This equipment is not comprised with the options Therefore this application note explains how to generate and adjust the required diffuse noise field with commonly available equipment For details on the operation of the UPV K9x software provided with option R amp S UPV K91 see R amp S UPV K9 R amp S UPV K91 Operating Manual 1 2 Ambient Noise Rejection ANR Tests Ambient noise rejection is a property of a telephone in sending direction Ambient noise rejection tests deliver a spectrally weighted ratio between the sending sensitivity of a telephone for speech signals speech send sensitivity and its sending sensitivity for background n
10. g the playback of the CD s Generating the Noise Field for Ambient Noise Rejection Tests 1GA51_ Oe 14 Literature 4 Literature e 3GPP TS 26 132 Speech and video telephony terminal acoustic test specification http www 3gpp org ftp Specs html info 26132 htm e R amp S UPV K9 R amp S UPV K91 Operating Manual http www2 rohde schwarz com en products test_and_ measurement audio UPV Manuals 22 2224 2224 html e Ultracurve Pro DEQ2496 User s Manual http www behringer com e Truth B2030A B2031A User s Manual http www behringer com 5 Abbreviations 3GPP 3 Generation Partnership Project ANR Ambient Noise Rejection HATS Head and Torso Simulator LRGP Loudness Rating Guardring Position MRP Mouth Reference Point 6 Ordering Information Ordering Information Type of instrument Audio Analyzer R amp S UPV or 1146 2003 02 R amp S UPV66 1146 2003 66 WCDMA 3GPP FDD signalling module R amp S CMU B56 v54 Versatile baseband board for WCDMA R amp S CMU B68 Rohde amp Schwarz Generating the Noise Field for Ambient Noise Rejection Tests 1GA51_ Oe 15 About Rohde amp Schwarz Rohde amp Schwarz is an independent group of companies specializing in electronics It is a leading supplier of solutions in the fields of test and measurement broadcasting radiomonitoring and radiolocation as well as secure communications Established 75 years ago Rohde amp Schwarz has a global presence and a d
11. ge of such a CD is provided on the download site of this application note 2 1 3 CD Player In principle one CD player is required for each pair of loudspeakers If equalizers are used which offer a delay function of at least 250 ms the delay can be used to de correlate the noise signals In this case each CD player can serve four loudspeakers An audio CD image with two tracks of two channel uncorrelated band limited pink noise is available for download on the download site of this application note 2 1 4 Equalizer Ideally the equalizer should be a graphic equalizer with 3 octave resolution Furthermore a sum gain control is required either in the equalizer or in the power amplifier s A delay function in the equalizer can be utilized to generate additional uncorrelated noise channels from the same source CD player see above 2 1 5 Loudspeakers Rohde amp Schwarz The loudspeaker frequency response should be sufficiently flat between 100 Hz and 8 kHz to allow equalization with the utilized equalizers In addition to the deviation of the loudspeaker frequency response measured in free field there may be effects of a non ideal room particularly in the low frequency region A suspension facility is needed for the speakers to allow their positioning in the required spatial arrangement Generating the Noise Field for Ambient Noise Rejection Tests 1GA51_0e 6 General Description 2 1 6 Amplifier required with passive loudspeakers
12. it to 3 dB Before all speakers are turned on set it to 15 dB This compensates for the level increase caused by the number of speakers Bypass Menu In both channels all modules except the graphic equalizer GEQ must be bypassed 3 3 3 Spectrum Adjustment Rohde amp Schwarz Place a calibrated diffuse field microphone at the MRP before starting the adjustment Connect the microphone via a suitable power supply e g conditioning Amplifier to R amp S UPV analyzer input 1 The HATS or test head must be removed before the adjustment Make sure to memorize the position of the MRP The HATS or test head must be put back later on with the MRP at the same position in the room Steps 3 3 3 and 3 3 4 have to be performed for each speaker separately Switch all speakers off Switch on only the speaker to be adjusted next Make sure which channel of which equalizer is assigned to the speaker currently activated 7 i FREQ GAIN bd OAC le 7 1 160 J15 6 kes ot SE LOE die Use button B to select the correct channel Use wheel 2 to select the frequency band Use wheel 1 to adjust the gain in 0 5 dB steps Start Calibration gt Ambient noise field in the R amp S UPV K9x program Start Adjust Spectrum Start the playback of the pink noise in the CD player The level scale of the spectrum display of the R amp S UPV K9x program auto scales such that the spectrum curve is centered within th
13. l arrangement are possible as long as the tolerance for the Spatial uniformity of the noise field is not exceeded If the test room is not ideally anechoic down to 100 Hz the low frequency response of each speaker may depend on its distance from the walls Fine tuning of the speaker positions may be required if the low frequency response cannot be equalized easily 2 2 5 Connections Connect the equalizer inputs to the appropriate CD player outputs Depending on the equipment this may be analog or digital S P DIF electric or optical TOSLINK If the equalizer s also offer a sum gain control active speakers may be connected directly to the equalizer outputs For passive speakers power amplifiers are connected to the equalizer output and the loudspeakers are connected to the outputs of the power amplifiers 2 3 Adjustment 2 3 1 Order of Adjustment Mark the position of the MRP of the artificial mouth in use and remove the HATS or LRGP test head respectively from the measurement room For the measurement at the MRP the measurement microphone may be positioned at the MRP before removing the test head For the measurements in 0 15 m distance another utility like the tip of a microphone boom is required to mark the MRP It is suggested to start with adjusting the speakers one after the other first in spectrum and then in level As the noise signals are not correlated the signals of the speakers will add up in power at the MRP Finally
14. oise room noise sensitivity The ambient noise rejection test as specified in 3GPP TS 26 132 assumes that the properties of the telephone are sufficiently time invariant to allow separate measurement of room noise sensitivity and speech send sensitivity Furthermore it is assumed that the rejection of the relatively uniform pink noise is somehow correlated with the rejection of other types of noise like street noise and background voices 1 3 Requirements on the noise field Rohde amp Schwarz According to 3GPP TS 26 132 the noise should be band limited between 100 Hz and 8 kHz The spectrum should be pink which means that the 3 octave levels within this frequency band should be independent of the center frequency of the 3 octave bands The tolerance of this spectral uniformity is defined to be 3 dB The total level of the noise should be 70 dBSPL A equal to 24 dBPa A at the mouth reference point with a tolerance of 1 dB The level and spectrum at the mouth reference point is to be adjusted in absence of the test head or HATS respectively Generating the Noise Field for Ambient Noise Rejection Tests 1GA51_0e 4 Rohde amp Schwarz Background The noise field has to be diffuse As a proof for the diffusity of the noise field it has to be assured that the 3 octave levels between 100 Hz and 3 15 kHz narrow band or between 100 Hz and 6 3 kHz wide band respectively are uniform within 3 dB within a radius of 0 15 m aro
15. ualization exceeding the range of the equalizer controls is required 3 3 2 Basic Settings of the Equalizer 3 3 2 1 3 3 2 2 Rohde amp Schwarz O Menu SAMPLERATE ei Ch D H ISE GAIN SELECT INPUT The input has to be set on the first page according to the connection used i e MAIN IN for analog connection from the CD player DIG In XLR for S P DIF connection and DIG IN OPT for Toslink connection If four speakers are fed from one CD via two equalizers in one of the equalizers only the delay has to be enabled for the main output and to be set to maximum This is done on page 4 of the O menu MEEC OFEET OMETER DIGITAL OELAY eee ann DELAY LEFT a ee Oe RIGHT iin nn j 300 mez rae Dn Set the unit to MSEC and the value for both channels to 300 Utility Menu GENERAL SETUP CONTRAST CHANNEL MODE a MONO EJ MOQE JFT IMIZEQ DAIN OFFSET EG 0 0 ATA N ISECORRECT ION OFF SHIH MESSACEEOx Oh RTA INPUT LINE LEVEL ee 0O dBu ATA INPUT MIC LEVEL anal PA dEeW YPa Generating the Noise Field for Ambient Noise Rejection Tests 1GA51_0e 11 3 3 2 3 Implementation with Specific Equipment e Set CHANNEL MODE to DUAL MONO This allows to set the equalizer for both channels independently e For alignment of one out of four speakers set GAIN OFFSET EQ to 9 dB For alignment of one out of eight speakers set
16. und the mouth reference point MRP It should be noted that this requirement can theoretically be fulfilled with a single speaker in sufficient distance from the MRP in free field whereas a real diffuse sound field also exhibits random direction of the sound incidence When measuring telephones with directional microphones different results of the ANR measurement have to be expected with different direction of the noise sound incidence Therefore it is recommended to use at least four loudspeakers with uniform spatial distribution for the generation of the sound field In measurement rooms with non anechoic conditions a higher number of speakers may be needed to achieve the required uniformity To avoid interference between signals from different loudspeakers each speaker has to be fed with an own noise signal which is not correlated with the noise signal of any of the other loudspeakers Generating the Noise Field for Ambient Noise Rejection Tests 1GA51_0e 5 General Description 2 General Description 2 1 Required Equipment 2 1 1 Equipment List Audio Analyzer R amp S UPV with options UPV K9 and UPV K91 Power amplifier s for passive speakers Connection cables 6 e Audio CD s with pink noise signal e CD Player s e Equalizers e Loudspeakers 2 1 2 Audio CD with Pink Noise Signal The audio CD should contain at least one sufficiently long track with two uncorrelated pink noise signals on the two channels An ima
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